This invention relates to an apparatus for monitoring and securing accessible danger zones in a fiber bale opener. The bale opener is of the type that includes a fiber tuft-detaching assembly which travels back and forth along a series of fiber bales. The monitoring and securing apparatus is of the type which has a beam transmitter and receiver spaced from one another in such a manner that upon interruption of the beam between the transmitter and the receiver a signal is triggered which may be used, for example, to immediately stop the machine movements that pose a safety risk. In case of a plurality of danger zones, the beam transmitters and receivers are so arranged relative to one another that the respective associated danger zone may be fully surrounded by the beam path between transmitter and receiver. A signalling device is provided which switches from one beam transmitting/receiving apparatus to another to arbitrarily activate and deactivate the securement of various danger zones.
In travelling bale openers of the above-outlined type, the danger zone to be delimited and secured is approximately as long as the length of the fiber bale series. Since in one type of bale opening systems two parallel bale series are present on either side of the travelling path of the bale opener, the detaching assembly is rotatable 180.degree. about a vertical axis to be situated over either the one or the other bale series and thus the detaching assembly passes from one danger zone to the other. The beam transmitters and receivers are arranged in such a manner that one danger zone is spatially continuously and entirely surrounded by the transmitted beam; the danger zone is that zone in which the detaching device is momentarily found to operate. A further securing apparatus surrounds the other danger zone by its beam at a time when the detaching assembly is situated in the working position in such other danger zone. In this manner, a delimitation and protection of that danger zone is at all times ensured in which the detaching assembly is situated and detaches fiber tufts from the fiber bales.
The detaching assembly comprises a height-variable, cantilever-like construction supported in a travelling tower of the bale opener which moves on rails along the bale series. After having consumed the first bale series on one side of the bale opener, the tower is rotated about a vertical axis 180.degree.. Then, after appropriate height adjustment, the detaching device may work on the second bale series while the area of the first bale series may be provided with a new bale series. This area, after switching the securing apparatus over to the second danger zone, is no longer secured by the optical barriers. Thus, at all times the bale opener works on one bale series while a new bale series on the other side of the bale opener may be placed in readiness.
In a more recent development concerning the detachment of fiber tufts from bales, a bale opener such as a model BLENDOMAT BDT 020 manufactured by Trutzschler GmbH & Co. KG, Monchengladbach, Germany is being used. In this type of bale opening system, the fiber bales are supported on a conveyor belt (hereafter also referred to as a "working belt") and the fiber tuft detaching operation occurs along an inclined top plane of the fiber bale series. In such an arrangement the detaching device operates along an inclined plane and new fiber bales are consecutively introduced into the fiber tuft removal process. Thus, while the first bale of the series being worked on is about to be consumed entirely, the last bale of the bale series which is being worked on just begins to yield the first fiber tufts. With the working belt there is associated an additional conveyor belt (hereafter also referred to as a "reserve belt") on which standby fiber bales are positioned. While the bale series being worked on is resupplied with standby bales from the reserve belt, the reserve belt has to be periodically provided with new standby bales. This is done by a shuttle carriage that travels back and forth from a carriage loading location to a location on the reserve belt where a standby bale is deposited from the carriage. The carriage receives a fiber bale in the carriage loading station from a transport vehicle, such as a forklift. The danger zone where risks of accidents are high thus extends from the travelling zone of the bale opener along the working belt, the reserve belt and the loading station for charging the shuttle carriage. For supplying bales to the loading station, usually a transport vehicle must enter and exit, without interrupting the process of supplying bales to the continuous bale detaching operation. At the same time, delimitation and securement of danger zones should be ensured.